Final answer:
Paragraph 4 of the excerpt reveals that when a government becomes destructive to the protection of unalienable rights, it is the people's right and duty to alter or abolish it, justifying the American colonies' decision to seek independence.
Step-by-step explanation:
The fourth paragraph of the excerpt from the Declaration of Independence primarily reveals the philosophy that when a government fails to protect the unalienable rights of its people, including life, liberty, and the pursuit of happiness or becomes destructive to these ends, it is not only the right but also the duty of the people to alter or abolish that government.
This reflects the Enlightenment idea that governments derive their power from the consent of the governed and emphasizes the necessary conditions that may lead to rebellion and the establishment of a new government. The paragraph clearly establishes the justification for the American colonies' decision to seek independence from Britain, highlighting a history of abuses and usurpations that led to the conclusion that British rule had become a tyranny over these states.